Carpal tunnel syndrome involves compression of which nerve?

• A. Median nerve of the wrist
• B. Radial nerve of the forearm
• C. Ulnar nerve of the elbow
• D. Sciatic nerve

Answer: (A)

Carpal tunnel syndrome occurs when the median nerve is compressed as it passes through the carpal tunnel at the wrist. This tunnel, formed by carpal bones and the transverse carpal ligament, holds the median nerve plus the flexor tendons. When the nerve is squeezed, you typically feel numbness or tingling in the thumb, index, middle, and the radial side of the ring finger, and you may notice weakness of the thumb muscles (the thenar eminence). The other nerves listed don’t travel through the carpal tunnel and therefore don’t produce the classic carpal tunnel symptoms: the radial nerve in the forearm would cause different sensory and motor changes, the ulnar nerve at the elbow (and its wrist path through Guyon’s canal) affects the little finger and intrinsic hand muscles, and the sciatic nerve lies in the leg. So the nerve involved is the median nerve of the wrist.